Anthony Mundine last night fulfilled a vow he made as a nine-year-old to win the world boxing championship his father Tony Mundine fought for and lost in Argentina in 1974.

Mundine the younger shocked American Antwun Echols on points over 12 rugged rounds at the Sydney Entertainment Centre and revealed after his victory that he had gone into the bout with a broken rib, an injury received in training a month ago.

Mundine's spectacular 20-fight boxing career never looked like coming to the brutal end that Echols had promised as the Australian claimed the World Boxing Association super-middleweight title.

Twenty-nine years ago, Tony Mundine snr, triple boxing champion of Australia from middleweight to heavyweight divisions, challenged Carlos Monzon for the world middleweight championship only to be stopped in seven gruelling rounds by the Argentinian in Buenos Aires.

That defeat was Anthony Mundine's burning torch within last night, having promised his father he would one day claim a world championship belt.

"I just want to thank every single human being - black, white, Asian, ethnic ... thank you," Mundine said afterwards.

'Maybe you didn't understand me and thought I was a bit cocky when I was playing football and came to boxing," Mundine said.

"Everyone said I couldn't do it, everyone said it was a dream. I know my first shot at it was unsuccessful. I am humbled in my achievements tonight."

Now, the likelihood is that Mundine will take a long rest and prepare for a continuation in boxing rather than make a comeback to his first love, rugby league.

Judge Prinit Prayadsab of Thailand gave Mundine the fight, 117-112; Michael Lee of Korea awarded it to Mundine, 117-112; and Erkki Meronnen of Finland gave it to Mundine, 115-114.

Echols went on the offensive early, attacking Mundine's body to drag down his defence. He shaded Mundine in the first round with his greater workrate.

But Mundine's boxing prowess emerged over the next four rounds, left-jabbing and hooking to the head of the American to take the rounds before Echols' head shots won him the sixth.

Mundine's jabs and hooks were taking effect and although Echols rallied in the ninth, 11th and 12th rounds, Mundine's skills, speed and defensive footwork were too much for the American.

He stopped Mundine in his tracks only when he knocked out his mouthguard in the last round with a heavy right to the jaw.

Echols entered the ring to the Australian sporting anthem, Men at Work's Down Under, holding the American stars and stripes and, in an interesting twist, the Australian ensign. He was smiling and relaxed as Aboriginal dancers performed in the ring, but soon the drama left him strained of face.

Mundine came in behind an Aboriginal flag and the national ensign, looking tense but superbly conditioned.

In the ring after his crowning, Mundine said: "This is a blessing for me and I want to give credit to Antwun. Before the fight, I had a virus and was not 100 per cent. But this time, the other thing that people didn't know was that I have been carrying a broken rib for a month.

"I went into the fight knowing that if I didn't have the fight a lot of questions would be asked. I was worrying about my rib, worrying about my condition. I had to overcome so many obstacles. I had to be very focused, protecting my rib."

While Echols charged forward throughout the fight, Mundine picked him off with spanking lefts and the occasional right hand, making Echols' left eye swell.

Mundine, 28, turned to professional boxing 38 months ago after a successful rugby league career with St George Illawarra, making a brief appearance for NSW in the 1999 State of Origin series. That controversial change provided boxing with a flood of headlines and put new life into an ailing sport.

Mundine won 18 fights before last night's bout, 14 by knockout, his 2001 loss being by knockout to German Sven Ottke. Echols came in with 26 knockouts against 34 opponents, with four losses and a draw.